(Business 2.0) – An espresso shot isn't the only thing that provides a jolt in the new $2.25 Wolfgang Puck Gourmet Latte. It's also the baked limestone pebbles tucked into a chamber inside the hard-plastic container. Hitting the "Start" button shoots a couple of ounces of water into the chamber, triggering a chemical reaction that generates heat. In six minutes your latte is a piping-hot 145 degrees. The Wolfgang Puck drinks are just the start. San Diego-based OnTech, which patented the heating system, has already rung up 20 million orders from various makers of soups, cocoa, and other on-the-go beverages. — ELIZABETH ESFAHANI